Winter waited until the busy holiday season to arrive, and it isn't letting up yet. After a second bout of icy precipitation Wednesday, more snow, sleet or freezing rain is possible over the weekend.

For the second time in three days, accumulating snow took local forecasters by surprise Wednesday, covering pavement, snarling traffic and delaying flights. Forecasts had called for mostly cold rain both Monday and Wednesday, but air more frigid than expected meant heavy snow at times both days, particularly in areas north and west of Baltimore.

Another mystery storm could move from the Gulf Coast through the Mid-Atlantic Saturday, potentially bringing with it a range of frozen precipitation. At this time of year, though, precisely predicting what falls where is hard to do more than a matter of hours in advance, as Monday and Wednesday's storms showed.

"There's a finer line than what we can put into the forecast a day in advance," Bryan Jackson, a meteorologist with the National Weather Service's Baltimore/Washington forecast office, said of the divide between rain and wintry precipitation. "The message we've been saying is snow and sleet, changing into rain. In both cases, the snow did accumulate across the Baltimore area before changing into rain."

In the meantime, more treacherous weather is in the forecast for Thursday. The weather service issued a wind advisory from 9 a.m. to 6 p.m., with northwest winds of 20-25 mph and gusts up to 50 mph, potentially downing trees and power lines.

The snow was part of a storm system that included tornadoes, and stretched from Michigan to Florida. It has been blamed for seven deaths and tens of thousands of power outages so far.

"It is a significant storm in terms of its size and its range of impacts from severe weather to winter weather," said Chris Vaccaro, spokesman for the weather service.

Snow started accumulating Wednesday morning around the region, blanketing parts of northern Baltimore County and Carroll County with about 3 inches, according to reports made to the weather service. In Baltimore City and Howard County along Interstate 95, snowfall totals were closer to 1.5 inches, with half an inch or less close to the Chesapeake Bay in Dundalk and Severna Park.

In Western Maryland, snow totals were heavier, with 6 to 12 inches across Allegany and Garrett counties.

By early afternoon, warmer air blowing over the region about 2,000 feet above the ground turned the snow into rain, freezing rain and sleet in the Baltimore area, Jackson said.

Thousands of residents throughout the region had their power knocked out, most by wind and heavy rains, on Wednesday evening, according to Rachael Lighty, a Baltimore Gas and Electric Co. spokeswoman.

Nearly 2,000 customers, mostly in Anne Arundel,Baltimore and Harford counties, remained without power as of 10 p.m. Nearly 4,500 had their power restored after previously experiencing outages.

BGE was estimating that power would be restored to most customers by 11 p.m. Wednesday, but "that might change depending on the weather conditions," Lighty said.

BGE advised Wednesday night that it also expected more outages due to high winds Thursday morning.

Roadways across the state were snow-covered or wet and slushy, according to the State Highway Administration. Snow covered roadways in the Hereford and Westminster areas, with isolated spots of snow coverage on roads in Howard County and parts of Baltimore and Anne Arundel counties. Roadways were wet around Baltimore City and around both Baltimore harbor tunnels. The state transportation department also reported flooding along Route 40 near Edgewood.

State highway officials reported 83 accidents around the state between 6 a.m. and about 5 p.m. but did not have information on the number of incidents in a normal day. During the morning rush hour as snow began to fall, there were a significant number of single-vehicle accidents — "a good indicator drivers were probably going a little too fast for conditions," spokeswoman Lora Rakowski said.

Near Bel Air, a snow plow truck ran into two utility poles on Route 924 near the entrance to the Harford County Detention Center, knocking out power there for about four hours. Route 924 was closed during the early afternoon as wires blocked the road.

For Westminster resident Wendy Casker, her normal 45-minute commute home grew to 21/2 hours when she decided to leave work in Laurel at 10 a.m., during the height of the snowfall. One delay came when she helped push a stuck BMW near the intersection of Routes 32 and 99 near West Friendship, and mostly, drivers were slow going, she said.

"I was behind him and couldn't move around so I figured I might as well help him," Casker said. "People were driving as courteously as they could. I was half expecting to get mowed down by a Suburban or something, but that didn't happen."

State highway officials warned that all roads could become treacherous overnight Wednesday, with temperatures expected to drop to the mid-30s in Baltimore and colder outside the city.

"People who are out tonight need to be really careful because whatever is on the ground is going to freeze," state highway spokeswoman Sandra Dobson said Wednesday.

Around the nation, airlines had canceled more than 1,800 flights, according to the airline monitoring website Flightstats.com.

A tornado watch had been in effect for part of the day Wednesday in eastern North Carolina and northeastern South Carolina. By Thursday, the storm could dump 12 to 18 inches of snow from the lower Great Lakes to northern New England, the National Weather Service said.

On Christmas Day alone, the weather service received 34 reports of tornadoes in eastern Texas, Alabama, Louisiana and Mississippi, Vaccaro said.

In Baltimore, the mix of precipitation was a confusing and cold combination that prompted people waiting at bus stops to don puffy winter jackets to insulate themselves and carry umbrellas to protect themselves from the rain.

The weather was cold and wet enough to make framing contractor Steve Kirby "hate it" but not bad enough to keep him and his crew at home instead of hoisting long planks of wood through a second-story rowhouse window for a rehabilitation project near Patterson Park.

"Your hands get numb," said Kirby, who works for Soperbuilt Woodworks of Baltimore.

But some took advantage of the snow. There was enough on the ground Wednesday morning to allow Kyoko Duke, 8, her brother Savon Elder, 10, and their father, LaMarre Elder, 29, to build a snowman outside their door on South Ellwood Avenue in Highlandtown.

The kids' stepmother had pitched them the idea while flakes fell before 11 a.m., and the entire family joined in, grabbing all the snow they could find on the sidewalks and across the street at Patterson Park. For half an hour, Savon and Kyoko gave up playing with the new Xbox and Monster High School House doll set to create a body of giant snowballs that they adorned with a carrot and red scarf and topped with a blue beret.

But by noon, the "wintry mix" was more sleet than snow and the kids were back inside and in their pajamas watching the animated movie "Monsters Vs Aliens" on TV.

Sled tracks ran up and down the hill outside Greenwood Mansion on the Baltimore County Board of Education grounds in Towson. But no sledders could be found Wednesday afternoon. The weather had shifted from snow to sleet to rain, driving them all back inside.

Forecasters expect one more storm system to move from the Gulf Coast to the Mid-Atlantic and Northeast over the weekend, but the details are proving difficult to predict, according to the weather service's Hydrometeorological Prediction Center in College Park. The storm could move more quickly than previous systems, though precise snowfall predictions depend on its ultimate track, strength and timing, according to a forecast discussion posted Wednesday morning.

The weather service's local forecast office is calling for a chance of more ice, rain and snow from Saturday morning through early Sunday.

Forecasters are predicting some snow accumulation around the Baltimore area Saturday, but just how much and how far south it could fall will remain somewhat of a mystery for perhaps another day. As of Thursday afternoon, though, it was looking like a snowy Saturday is likely.

Historic flooding and the coldest temperatures in decades made weather headlines in Baltimore in 2014. Rainfall records were set in April and August, and after a frigid winter, the summer was comfortable and fall cool. The year is expected to be the coolest and wettest here in years.